public class test2 {
        public String removeDuplicates(String s) {
            //利用栈
            Deque<Character> stack = new LinkedList<>();
            for(char ch:s.toCharArray()){
                if(stack.isEmpty()){
                    stack.push(ch);
                }else{
                    if(stack.peek()==ch){
                        stack.pop();
                    }else{
                        stack.push(ch);
                    }
                }
            }
            StringBuilder res = new StringBuilder();
            while(!stack.isEmpty()){
                res.append(stack.pop());
            }
            return res.reverse().toString();
        }
}
